§1.1 Field of the Invention
The present invention concerns on demand peer-to-peer (P2P) video streaming. More specifically, the present invention concerns improving peer-to-peer based video streaming network to provide reliable and high performance video-on-demand for peer devices that may have common residential network access means.
§1.2 Background Information
Although today most pre-recorded video is distributed by broadcast, cable and satellite television, the present inventors believe that over the next few decades these traditional means of video distribution will be supplanted by Internet video streaming. When this happens, instead of having access to only a few hundred channels, users will be able to search and view, on-demand, enormous libraries of video content stored in the Internet. The present inventors believe that the Internet will not only facilitate the distribution of vast libraries of content, but will also support a wide range of video formats and visual qualities, ranging from high-bit rate DVD quality video to low-bit rate video suitable for hand-held wireless devices.
One of the major challenges in realizing this vision is the deployment of cost-effective Video Streaming Networks (VSNs) in the Internet. Broadly speaking, there are two generic architectures for a VSN: infrastructure-based video distribution; and P2P-based video distribution. An infrastructure-based VSN would deploy a dedicated set of servers to store and distribute content to clients. As with Content Distribution Networks (CDNs) today (such as Akamai), when a user requests a video, the VSN would redirect the client to one or more of its dedicated servers. These servers would then stream the video to the client. Such an infrastructure-based VSN is likely to be prohibitively costly, both in terms of server cost and Internet-connection cost.
The present invention concerns P2P-based VSNs, where users' peers store and stream video to the requesting client peers. Some of these peers might be connected to the Internet via residential access networks such as digital subscriber line (DSL) and cable, while other peers might be connected via high-speed Ethernet connections. The cost of these peers and the Internet access would be borne by the users rather than by VSN infrastructure companies.
Various features of the present invention address numerous issues surrounding the successful deployment of a P2P VSN. Such issues are introduced below.
In P2P systems, nodes may disconnect from the system at anytime without warning. One of the major challenges with a P2P VSN is the distribution of high-quality video without glitches when the distribution devices can disconnect from the Internet without notice. Special care must be taken in designing video source coding schemes that are appropriate for streaming systems in which server nodes can disconnect without warning. Another important challenge relates to the relatively low upstream bandwidth of many of the peers.
A user should only be able to view copyrighted content when authorized to do so.
There are, naturally, a variety of security threats that surround peer-driven content distribution. For example, to earn incentive rewards, server peers can attempt to falsely claim to have streamed requested content. As another example, to avoid making payment, client peers can falsely claim to not have received the content. Server peers, client peers, or third parties can attempt to sabotage the system via traffic-flooding denial of service (DoS) attacks and via content pollution attacks.
Recently, several video multicast systems making use of peer coordination have been studied. However, in these systems, the video content is stored in a central server and the peers merely help to relay the video originating from the server by forming one or several multicast trees. Thus, peers only help each other when they watch the same video.
In view of the foregoing, it would be useful to provide an improved peer-driven VSN.